1.3.5 Memory Storage Media

Question 1

What is primary storage

Answer 1

RAM/ROM
Directly accessed by CPU
RAM is volatile
ROM is non-volatile

Question 2

What is secondary storage

Answer 2

HDD/SSD
Not directly accessed by CPU
non volatile
stores data that can be accessed later

Question 3

What is offline storage

Answer 3

DVD, CD, USB, flash memory
non volatile
can be disconnected from the computer

Question 4

What is RAM

Answer 4

Random Access Memory
Primary storage
Stores data/programs/instructions that are currently in use
Volatile
Easily expandable

Question 5

What is ROM

Answer 5

Read Only Memory
Non volatile / permanent
Stores the boot program/BIOS 
Used to boot up the computer when it is switched
Fixed size

Question 6

What is virtual memory

Answer 6

When the RAM is full a section of the hard disk is used to store items in RAM that are currently not being used
This frees up space for new programs to be loaded
Slower than RAM

Question 7

What is cache memory

Answer 7

Temporary storage area between CPU & RAM
Stores frequently used instructions/data
Faster as data doesn’t need to be fetched from RAM
Uses faster SRAM
More expensive than RAM

Question 8

What is the difference between DRAM and SRAM

Answer 8

Dynamic RAM:
-Capacitors hold each bit of memory
-Need to be constantly refreshed with power to store bits
-Less expensive, higher storage capacity
Static RAM:
-‘flip-flops’ hold each bit of memory
-No need to refresh power
-Faster and consumes less power

Question 9

Magnetic Tape

Answer 9

Type of magnetic storage
Serial access medium – need to start reading from the beginning
Mainly used for cold storage
Pros: large capacity, cheap, takes up little physical space
Cons: slow to transfer

Question 10

Hard Disk Drive

Answer 10

Magnetic Storage
Data is stored on magnetic platters
Data is created by magnetizing ferrous particles on the disk
North and South represent 1s & 0s
Several platters with 2 surfaces spinning thousands of times a second
Disk heads on mechanical arms to read and write data

Question 11

SSD

Answer 11

Solid State Drive
Flash memory and is non volatile 
No moving parts 
Type of EEPROM
Used in phones/cameras

Question 12

SSD vs HDD

Answer 12

Price: SSDs are about 10 times more expensive than HDDs per MB
Power HDDs use about 3 times more battery power than SSDs
Capacity SSDs generally have a much smaller capacity then HDDs
Portability SSDs are smaller and lighter than HDDs
Speed SSDs are almost twice as fast at reading and writing
Noise SSDs are silent whereas HDDs make spinning disc sounds
Durability SSD has no moving partss and is not vulnerable to knocks
Reliability Both are highly reliable, but …. HDD has greater longevity for r___/wr___ functions

Question 13

How is data written to optical storage media e.g CD

Answer 13

The disc is rotated 
A laser beam is used 
The laser beam makes pits and lands 
The data is written in concentric tracks 
The pits and lands represent 1s and 0s

Question 14

CD vs DVD

Answer 14

DVD has a larger capacity
Shorter laser wavelength
… means pit/land size is smaller so more data in the same space
Uses dual layering so there are 2 recording layers

Question 15

DVD-R, DVD-ROM, DVD-RW

Answer 15

DVD-R: recordable, fills up overtime then read only
DVD-ROM: Read only
DVD-RW: rewritable

Question 16

What is DVD-RAM

Answer 16

Concentric tracks opposed to 1 spiral track
Simultaneous read and write operations …up to 100 000 times
Great longevity -> ideal for archiving
Similar operation to HDD

Question 17

Blue ray vs DVD

Answer 17

Blue Ray: 
    -Blue laser 
    -Larger storage capacity 
    -Single polycarbonate layer 
    -Faster transfer rate 
DVD: 
    -red laser 
    -smaller storage capacity 
    -2 polycarbonate layers